Subject F
by TheSocialBookWorm
Summary: Sans didn't expect the sound he heard to be two near identical humans. He really didn't expect the humans to have two familiar looking hand plates drilled into the back of their hands as well. He couldn't bring himself to leave them behind if they had gone through even a fraction of what he and his brother had been through. Handplates AU where Gaster never fell into the Core
1. Prologue

AN-Me? Obsessed with Undertale? Nah, nope, no way. But just you know, a random idea that I hope you peps will enjoy. *glares at FF as I still struggle with formatting* Critics are always welcome as are reviews!

Disclaimer- Undertale belongs to Toby Fox

Prologue

 _You cried out as the pain rippled through your body. You struggled against the restraints, your soul floating gently above you as the machine descended into it. A second scream started in your head as the blade started to slice a layer off of the top of the red heart._

 _You scrambled to hold onto Chara as the other child's voice got quieter and quieter._

" _Chara!" you screamed desperately as your one comfort in this horrid place was taken from you. Your eyes rolled up into the back of your head as the pain became too much, and you missed the white bones that reached out to grasp the tatters of a soul that had been pulled from your own._

* * *

 _You danced out of the way from the desperate monster's attacks. Without Chara in your head, you had no idea what it was called, but the skeleton wanted you to fight it. The thought of hurting the gentle looking creature made you sick, so you simply dodged, choosing Mercy at every opportunity._

" _Subject F," came the harsh voice. "You are to fight back."_

 _You knew what was to come, but you were determined not to let this place break you, and you shook your head in refusal._

" _Save," came the angry command, and you braced yourself for pain as you complied. You had only refused once._

 _The familiar yet unfamiliar scream startled you, and your head snapped up to look at the observation deck. Your eyes grew wide at the the other child writhing on the ground, and you just knew who they were._

" _Chara," you yelled, taking a step forward out of instinct._

 _The other child went limp, and their soul floated up, and shattered before you could get a good look at it. You felt sick, your stomach heaving more than when something like this happened to you._

" _Subject F," the scientist said, and you snapped your eyes over to him. "You are to comply to my commands. Fight. Your. Opponent."_

 _You were shaking, tears snaking down your face, as you shook your head._

" _Load." You did so, and the screaming started again._

" _Fight." But you refused._

* * *

 _You pressed yourself into the corner of your cell, the cool concrete feeling nice against your overheated skin. You picked at the sloppy stitches on your arm from where the scientist had peeled back your skin to study your muscles. You thought you should feel horrified but you just felt numb to it at this point._

 _There was a clatter as the door to your cell opened, and your heart sank at the idea of another test so soon. You pulled your knees to your chest as a silent rebellion, and glanced up through your bangs. The door didn't open very wide, and something was thrown in, landing with a thump as the door was shut one more. You crawled closer to it cautiously, and cried out when you saw the child there._

" _Chara," you sobbed, reaching out for the unconscious human. "Chara."_

* * *

" _Subjects S and P were never this willful," the scientist muttered to himself as he strapped the struggling Chara to the table next to you._

 _Chara snarled at him, "We won't break as easily as they did."_

 _You tried to prepare yourself for their scream, and were surprised when instead the skeleton reached for your arm. There was a snap, and you tried your best not to scream, whimpers escaping from your throat._

" _You bastard!" Chara screamed, surging against their restraints. "They didn't do anything!"_

 _The scientist reached out and broke your left pinkie finger. You did scream that time, but cut it off at the look on Chara's face. Tears made it past your eyes as you squeezed them shut to try and block out the pain._

" _Stop it!" You locked onto Chara's voice to try and comfort yourself, to remind yourself that you weren't just a test subject._

 _Another snap as your ring finger was broken. "I said stop it!"_

 _Your middle finger was the next to go._

 _Chara's voice broke into a whimper. "Please." Your hand was mostly numb so your index finger didn't hurt that bad as it was bent out of shape._

 _They sobbed, and the scientist said in his cool voice, "Subject F would be in better shape if you would cooperate, Subject C."_

 _You cracked your eyes open to see the apologetic look they sent your way, and you gave them a small nod._

" _My name is Chara," they snarled with all the determination they could muster. "And they are Frisk."_

 _Your fingers weren't the only bones broken that day._

* * *

 _You were exhausted, stumbling behind the scientist for the third time that week. (At least you thought it was a week, time seemed to be slipping from your grasp.) He was pulling you for the tests more and more, choosing you over Chara as long as it didn't involve killing something. You were retreating farther and farther into yourself while Chara fought back harder and harder._

 _You stood at the end of the room the scientist lead you to, surprised when you saw Chara at the other end of it. He disappeared through the door, and left you two standing there as he made his way to the observation deck._

 _Your stomach churned in apprehension and confusion. He had never done anything like this before, and that worried you._

 _Chara gave you a weak smile before glaring at the scientist on the observation deck._

" _Subject F engage Subject C," the scientist's voice rang out with a finality that it hadn't have before. Horror crossed Chara's face, and you were sure it was echoed on your own._

" _No." Chara glanced at you in alarm. You rarely spoke out anymore, and they beamed at you in pride for doing it now. It warmed your numb body, and your own smile twitched back at them._

" _Subject F," the cold voice sent shivers down your back. "Save."_

 _The word echoed with the horror that always followed when you did so, but it was worse if you didn't. You reached your shaking hand out to your menu, the Reset button was blacked out as it always had been since you had fallen down here. You didn't know what it did._

 _You pressed the button, and your whole body began to shake. Whatever would happen next would be horrifying._

 _That strange black magic that he used crept from the walls, and wrapped around your arms, spreading out like webs. It tightened around you, and slowly to your horror, it contracted, bending your arms. It crept down your body, until it was moving without your control._

 _It made you race forward and lash out at Chara. Chara stumbled out of the way, anger and horror in their eyes. They ducked and weaved around the attacks, and you were thankful that you had never been good at fighting. Chara's brow furrowed with frustration as they tried to decide what to do._

" _Subject C," the scientist almost growled, "Engage."_

" _No!" Chara shouted back at him, fists clenched in defiance._

 _Your body froze against your will, and you struggled against the control. Chara relaxed slightly, probably thinking the worst was over._

 _That hope was quickly dashed._

 _Your eyes widened as your arms slowly reached up and wrapped around your throat, tightening by fractions. Chara screamed in horror and anger at the scientist as you began to gasp and then stop breathing altogether._

" _I won't hurt them!" Chara shouted. "Nothing you do can make me do it!"_

 _You blinked sluggishly as you vision blurred, wishing you could tell them it would be alright. You knew that it was his fault, not theirs. But you didn't get the chance to tell them that as you finally lost consciousness._

" _Load."_

* * *

 _This was the worst thing he could do to you. The blank white room where you were left alone for days on end, when not even the scientist would enter. Suffocating silence as the walls pressed in on you, and the hours passed like years. Nothing happened. There was no one. Only you._

 _The first time he had done this you had only made it through without screaming because Chara had still been attached to your soul. The second time you were alone, and had screamed your throat raw as time passed and you remained alone._

 _This time, you curled into yourself, retreating to your head, and the imaginary time when you and Chara had been safe. (You were never safe.) Your eyes dulled, and you didn't even get up to get the periodical food drops. You felt numb, your mind trying not to snap from the isolation._

 _Whispering, you called for help._

 _But nobody came._

* * *

" _What is your name?"_

" _...Frisk."_

 _Pain, a scalpel slicing through muscles until they hit a nerve. You screamed._

" _Load."_

 _The pain vanished._

" _What is your name?"_

" _... ...Frisk."_

 _Pain._

" _Load."_

" _What is your name?"_

" _... … ...Frisk"_

 _Pain._

" _Load."_

" _What is your name?"_

" _Fri- Subject-" You tried to numb yourself._

 _Pain._

" _Load."_

" _What is your name?"_

" _...Subject F."_

* * *

 _You stay determined. You don't remember why._

" _Save."_

 _Electrocution wasn't like they showed on TV._

" _Load."_

 _Drowning was worse._

" _Load."_

 _Arms torn off by a rampaging monster._

" _Load."_

 _He wanted to see what a human brain looked like._

" _Load."_

 _Punishment for Chara._

" _Load."_

 _He wanted to see if you could die by your own hand._

" _Load."_

 _He wanted to break you._

" _Load."_

 _He wanted to break Chara._

" _Load."_

 _You couldn't remember if death is a bad thing._

" _Load."_

 _You were just a test subject._

" _Load."_

 _A lab rat._

" _Load."_

 _Chara still believed in you._

" _Load."_

 _Acid was one of the few things that still hurts._

" _Load."_

 _You break._

* * *

 _But Chara doesn't._

 _._

 _._

 _._

 _._

 _._

 _._

 _._

* * *

 _Their hand was warm in yours as you ran._


	2. Chapter 1

Disclaimer- I don't own Undertale

Many Thanks to TheFlameRose for Beta-ing

Thanks also extended to the guest reviewer who pointed out that the formating flipped out on me TT

*Frustrated screaming over FF's formating*

Chapter 1

Sans sighed, running a hand over his skull as he leaned against the wood of his sentry station. Something about today just felt off, and it was setting the skeleton on edge. It made him want to track his brother down just to be sure that Papyrus was safe. He yawned, deciding that he was just tired and that a nap would be all he needed to get rid of his anxiety.

He was just dozing off when a branch broke nearby, snapping him to attention. He slowly straightened, knowing that it was probably just a member of the canine unit, but not really believing it. Undyne had started to send the entire unit into the area claiming it as training, but Sans had a feeling that there was more to it than that. He had a theory, and the minute it looked like it would be confirmed, he was grabbing Papyrus and making a break for it-

-Or moving to Undyne's house. The search for Gaster had died down as people began to assume the ex-Royal Scientist had fallen down, but as Undyne met Papyrus and learned what had happened….. Well. The Captain of the Royal Guard was going to see the monster's dust herself before she let up on the search. She probably hated the man more than Sans did at this point. Watching Papyrus wake up from nightmares had only made it worse.

But since Sans didn't know for a fact that it was Gaster they were looking for, and he trusted Undyne to tell them if there were any developments, he was trying not to worry too much.

Another branch snapped, this time followed by muted cursing, and Sans sat up straighter. He tried to reason it off as a Moldsmal or the Snowdrake that he had seen wandering around the forest, but he found himself standing anyways. He teleported in the direction of the sounds so that he didn't alert whoever it was by walking through the snow.

He appeared on a tree branch nearby, and almost fell out of it as he caught sight of a small human tugging another one along. They looked like twins, with brown hair though the one in front's was slightly curlier. The one in front walked with a noticeable limp, but was still moving faster than the second one. They were dressed in familiar green gowns that had Sans reaching out to hold onto the tree trunk to steady himself.

The second human stumbled, and the one pulling them along froze, turning back to look at them.

"Come on Frisk," they said urgently, "We have to keep moving, please."

The second human, Frisk (?) didn't respond and the first one growled under their breath, tugging them to a tree and pushing them into a sitting position gently.

"Your arm," they demanded, and Frisk held their right arm out. Sans felt bark snap under his hand as he caught a glimpse of the mess of scars and bandages on their palm.

The first human was muttering to the second one, "You're not going to get full mobility from that again are you?"

There was no response, and they sighed.

"Frisk, please," the human pleaded, "We're free. You don't- It's not- We can-" They growled, gripping at the snow beneath their hands. They took a shuddery breath. "We're safe. You're safe. I'll keep you safe. I promise. Please Frisk, please." They broke down sobbing, curling into themself. Slowly, the second human looked up, and Sans's breath caught. Their brown eyes were empty, dead.

Carefully, Frisk reached out, and laid their good hand on the other human's arm. The first human surged forward gathering them up in their arms. Sans hesitated as they calmed down. He doubted that his usual approach of humor would help in this situation. He shifted as he thought, knocking some of the snow and ice from the tree he was on.

Both humans' eyes snapped up to look at him and he winced. Red eyes glared at him with all the heat they could muster as they shoved Frisk back, spreading their arms out to protect them.

"Back off!" they shouted, baring their teeth.

Sans jumped out of the tree, and shoved his hands in his pockets. "that's not very n-ice. only a really cold monster would leave two children alone without help."

The human stared at him, blinking at the puns, and Sans felt his smile grow just slightly at the reaction. Surprise was better than anger in his opinion.

The human wiped the look from their face. "We don't need help. We don't want help!" They tugged on their companion's arm. "Just leave us alone."

"hey," he said taking a step forward. Red eyes snapped back to his face and harden in a way that made a chill go down Sans back.

"Take another step closer and I'll kill you," the child said quietly. Their body tensed, ready to move at the slightest provocation, and Sans raised his hands slowly into the air as a gesture of peace. Their eyes locked onto the metal plate drilled into his left hand and grabbed the other human's hand breaking into a run.

"wait! kid!" he called, and teleported in front to them. They skidded to a stop, alarm clear on their face. They shoved the other kid in another direction.

"Run Frisk! Go!" they snarled as Frisk hesitated. Sans thought that his eyes flickered black at the reminder of when he had done the same thing for Papyrus.

* * *

"run pap! go!" Sans snarled, placing himself between the fire monster and his brother.

"BUT BROTHE-" Papyrus tried to protest, hesitating.

"no," Sans said sharply, "i'll be fine."

The small pattering of feet behind him was the skeleton's only way of knowing that his brother had left. Sans glared at the monster in front of him just daring him to try and go after the younger one. The adult raised his hands in a symbol of surrender, his eyes flickering between Sans and the fleeing Papyrus.

"I only wish to help," the monster said.

"and what do you want for it?" Sans shot back.

"Nothing," came the steady, patient reply.

"liar!" Sans yelled, clenching his fists, and he readied his magic in case the monster tried to do anything. A small body collided with his back, and he flinched.

"PLEASE BROTHER," Papyrus said, "IT CAN- THERE CAN BE NICE MONSTERS AS WELL."

Sans closed his eyes, and when he opened them he glared at the monster in front of them. "fine," he bit out. But the minute it looked like something was going wrong, they were leaving.

* * *

"look, kid," he tried, his eyes flickering between the two humans. "i don't want to hurt ya. i just-"

"Shut up!" they shouted, "You look like him!" Sans twitched at the reminder. "And you have that plate. You're probably just going to take us back to him! I'd rather kill everyone down here than go through that."

Sans blinked, trying to work through why that phrase was weird to him. Most monsters would have said that they'd rather die. Maybe they thought killing was worse than dying? But that would contradict their statement earlier and the ease that they had threatened him with.

"i don't want to fight," Sans tried again.

"I won't." They both startled at the sudden quiet voice. It was scratchy from disuse, and the first human whirled around to look at Frisk. Frisk's expression hadn't changed, their eyes still dull, but there were a couple of tears rolling down their cheeks.

Something in the other human seemed to break, and they reached out to wipe the tears away. "You don't have to Frisk. We're free. You never have to fight-."

"I won't." Sans started as the human repeated their statement again.

Red eyes stared into brown. "I'm right here Frisk. Why won't you come back from wherever you are?"

There was no reply, and the human started, whirling to face him again. Anger flashed in their eyes, but drained away as quickly as it had appeared.

"If you're going to take us back, let's just get it over with," they muttered.

"what's your name kiddo?" Sans asked, wanting to steer the topic away from Gaster altogether.

"Subject F," the second human said, almost like it was automatic and without thought.

The second human flinched before staring up at him with determined defiance. "Chara. And Frisk."

"well, uh chara. you look like you could use some food," Sans offered, stuffing his hands into his pockets. "you two want a couple of hot dogs?"

Chara's face gave way into confusion. "Hot...dog?" Then they looked at him with a triumphant sort of anger. "You think we would eat something made out of dog monster? Maybe you want to see how we'd react? Well too bad, we're not moving from this spot."

Sans felt a flash of anger at Gaster, and tried to keep it from showing on his face. The scientist just couldn't leave others alone, just couldn't stop messing with people's heads. Sans forced himself to shrug. "offers open if you ever want it. just stop by my station." He waved a hand in the direction of his sentry station. "and you should keep an eye out for the traps and puzzles in the area."

He wondered if this frustrated feeling of helplessness was how Grillby had felt the first time that he'd had met the skeleton brothers. The humans weren't just going to follow him home, and trying to force them to do anything would be counter productive. They had to trust someone before they could get any help, and trust would take time.

Time that Sans wasn't sure they had.

He mentally noted that he would have to inform Grillby and Papyrus about the humans, and probably Undyne as well. The skeleton winked at the humans before turning to go.

"What-? Where are you going?" Chara asked distrustfully.

"my station," Sans said mildly.

"You said it was in the other direction!"

"shortcut," Sans replied cheerfully before walking away and teleporting as soon as he was out of sight. There were things he had to do.


	3. Chapter 2

A/N- *Cackles*

Many thanks to TheFlameRose for Beta-ing!

Disclaimer- I don't own Undertale

Chapter 2

The woods were crawling with monsters after that, and Chara growled under their breath as the dog monster clanked by in its huge armour. There had also been another skeleton, taller than the last, but shorter than the scientist, that kept coming back. It had yelled something about promising not to capture them before leaving a plate of something. Chara refused to touch it. Boxes were showing up along the edge of the paths near the forest, all of them filled with clothes, blankets and food. Chara avoided those, despite the temptation of getting something warm to wear.

Some monsters had lost a couple of blankets that Chara had taken, having found them in the branches of some trees and branches. It worked to keep the two humans alive, and even almost comfortable when they were in the hollow tree Chara had found. They had lined it with one blanket and given the other one to Frisk, tying the cotton around their shoulders. But no matter how hard Chara tried, Frisk kept getting colder and colder. The lack of food was starting to take its toll, and soon Chara may be forced to risk the food that the monsters had left out.

The dog moved on, and Chara laid a hand on Frisk's shoulder, feeling the minute tremors coming from their adoptive sibling. Frisk glanced up at Chara with dead eyes, but at least they were responding to Chara again. The two humans stumbled away, Chara's feet, cracked and bloody from the cold, leaving bloody footprints as they walked. Chara led Frisk a different way towards where they were staying, stumbling out onto the road. Chara noticed the small wood structure nearby, they grit their teeth, and then blinked.

The structure was empty one moment, and the next, the short skeleton that had talked to them was propping its feet up on the wood. Chara stumbled back in surprise, shoving Frisk behind their back. The movement caught the skeleton's attention, and it turned its head to face the two humans.

"oh, hey there. chara and frisk, right?" it asked, and its grin widened. "things chill for you lately?"

Chara twitched at the pun, and then stiffened as the skeleton's attention shifted to the human just past Chara. Chara shifted to block its view of Frisk, growling under their breath as they mentally warned it to back off.

"well," it said, "at least one of you enjoys my jokes."

Chara felt their throat tighten, and they forgot about being careful around monsters, about keeping their guard up so they could react if any one tried to take the two of them back to the lab. Chara whirled around, and stared at the smile on Frisk's lips. It was more of just a slight tilt upward, easy to miss if someone wasn't looking for it, but it had the effect of making Frisk's face actually look alive.

The smile fell as soon as Frisk noticed that both Chara and the skeleton were staring at them. Frisk blinked, and once again they were completely buried in their head. Chara sighed, placing a hand on Frisk's head.

"I'm so proud of you," Chara whispered. "For being Frisk instead of Subject F even if it was just for a second."

"uhhh," the skeleton brought Chara's attention back to it, and Chara glared at it, though they couldn't work up the same amount of heat as before. It had been responsible for that moment with Frisk after all.

"What?" Chara snapped.

"you really care about them don't you?" the skeleton murmured, more to himself than to Chara, and that set the human on edge. Chara didn't want to confirm anything in case the skeleton wanted to use Frisk against them. They inched back, trying to get Frisk to move away from the skeleton. It didn't move, but its eyes watched them in a way that made Chara's skin crawl.

"BROTHER!" a voice yelled, and Chara jumped, grabbing Frisk's wrists and taking off at a run in the direction they had come from. It was away from the hollow they stayed at, but it was also away from the monsters. Chara's injured leg throbbed as they tried to run without a limp. Frisk ran behind them, the blanket flowing behind them as they ran, and Chara wondered if they should make Frisk run ahead of them. If Frisk was in front Chara could attempt to fight off the monsters while Frisk made their escape.

Chara glanced behind them, and cursed as their foot caught on a root. They pitched forward, dragging Frisk down with them as they fell. The two humans fell in a pile of limbs, and Chara clenched their jaw against the throbbing pain from their left leg. The two of them stood back up, and Chara glanced around, realizing with a sinking stomach that they had no idea where they were.

Whatever caused the light in the Underground was slinking away, the shadows growing longer. Chara shifted, turning in a slow circle as they tried to decide what to do. The simplest thing would be to follow their own footprints, but that would take them back to the skeleton. The skeleton that could follow the footprints to find them as well.

Chara felt hysterical laughter bubble up from their throat. They had messed up. They had one job. Chara couldn't even manage to protect the one person who mattered to them, and wasn't that just hilarious. They could destroy all they want, as shown from their growing LV from the lab, but they couldn't protect one thing.

They doubled over, clutching at their stomach as they laughed harder. All they had done was go from a violent demented ghost, to a violent demented doll that passed as human. Chara was distantly aware of the world growing cold around them, and the fact that they couldn't breath because of the laughter. Black started to creep in at the edges of their vision, sending them into a panic. Chara tried to cut off their laughter, only to find that they couldn't breath anyways as they descended into a panic attack

Pressure built on their chest, and Chara wanted to laugh again. They were going to die out here in the cold. Then Frisk would die, and they would find themselves right back in the lab as time rewound. Chara curled into a ball, hyperventilating. They couldn't do this anymore. Maybe Frisk had the right idea about giving up. But, Chara felt something warm that prompted them to struggle to stay awake. No, Frisk was still Determined, if they weren't they would have died already.

The thought of Frisk remaining Determined filled Chara with Determination as they slipped into unconsciousness.

* * *

Chara woke to an unfamiliar ceiling. They jolted upwards, knocking the stack of blankets on top of them off. Every part of them felt warm, but they chalked it up to the fact that they were indoors instead of out in the snow. The human scanned the room, noting the strange dolls, the bookshelf and the computer. They shoved the blankets the rest of the way off of them, and blinked. They weren't in that gown any more, instead a set of soft orange clothes was fashioned to hang loosely off of their body covered them. Their feet had been wrapped in bandages that wound up to their mid shins.

They climbed off of the bed, which was shaped strangely, the name of the thing on the tip of Chara's tongue, but kept slipping away. Chara headed straight for the door that was by the computer assuming that whoever had them would have put Frisk there. They pulled it open, and their breath hitched as they saw that is was just more clothes.

They whirled around and hurried towards the other door, realizing with a sinking heart that it was probably locked, and they had been separated from Frisk. To Chara's surprise the handle turned easily under their hand, and they pushed the door open. Low murmuring could be heard now that the door was open.

Their feet stung as they walked across the carpet to look out at the floor below. The first thing they laid eyes on was Frisk laid out on a strange looking bed that had three headboards made out of pillows rather than two. Frisk was covered in blankets as well, and a cloth on their forehead. Their chest moved up and down steadily, and Chara felt something in their chest relax as soon as they saw Frisk.

They glanced around, wondering where the monsters were, but hurried down the stairs to Frisk. Chara knelt down next to them, and placed a hand on their cheek. Frisk was covered in sweat from the heat, and Chara reached over to push the blankets off of them. The monsters could be trying to test how much heat a human could take again.

Chara's eyes flickered over to where the murmuring was coming from, and they leaned in that direction to hear even better.

"-dunno grillby. it could make things worse. you saw the state they were in."

"All the more reason to gain their trust."

Chara mentally snarled. Like they would ever trust a monster. They turned to their adoptive sibling and gathered Frisk up, settling the sleeping human onto their back. Frisk's hands hung over Chara's shoulders, and Chara held onto their knees. It was a struggle to stand with their injured leg but Chara managed it, wobbling as they tried to balance the new weight.

Chara's first thought was to go back to the room they were in before and barricade the two of them in it, but the monsters would find a way in eventually. Their eyes locked onto the door by the couch, that from the look of it led outside. They moved as quickly and quietly as they could, opening the door.

"papyrus? did you get-" the short skeleton glanced out of the room it was in, and its eyes widened as it caught sight of Chara with Frisk on their back. "kid-"

Chara slammed the door behind them and hurried through the snow in the direction their gut was tugging them in. They slugged through the snow, away from the town following the river as they went. The path felt familiar to Chara, though the human could have sworn they had never been Underground before Frisk fell.

Chara shook their head, and walked faster. It probably wasn't important.


	4. Chapter 3

A/N-Me: Ummmm... Muse Kitty? Don't you think this is a little dark?

Muse Kitty: Meow

Me: No, I know that it makes sense...at least I hope it does. And it does explain some things, but still...

Muse Kitty: Meow?

Me: What?! No! This wasn't me asking to work on something else- Wait where are you going?! You'd better not come back with an entirely new idea!

Many thanks to TheFlameRose for Beta-ing!

Disclaimer- I don't own Undertale

Chapter 3

The cold wasn't too bad at first. It tingled pleasantly on Chara's warm skin, and the bandages on their feet made walking more comfortable so they were moving at a pretty good pace despite the weight of Frisk on their back. Snow fell at a slow pace, but it was heavy which meant that their footprints would be gone within minutes. Their head was a little fuzzy, but Chara assumed that it was because they had only woken up a little while ago.

Frisk whimpered from on their back, and Chara tightened their grip on Frisk's legs. They didn't know why, but Chara felt like it would warm up the farther the two of them went, so they tried to pick up their pace. Chara thought they heard the crunching of feet in snow behind them, and their stomach dropped. They hadn't gone fast enough to escape the monsters and now they were going to be punished.

"Yo!" a young voice greeted from behind Chara. Chara turned to look at the monster coming up behind them, noting the lack of arms and striped shirt. "You sneaking out to see Undyne too?"

Chara hesitated, not sure which answer would be the least suspicious. Before they could answer, the monster continued. "It's cool! I won't tell anyone we snuck out if you don't."

Chara smirked, a fraction of the tension in their frame leaking out. Give and take was what they were used to. "Deal."

"So what happened to your friend?" the monster asked, glancing at Frisk.

"Oh. They're just tired," Chara lied easily. "They're always so lazy, all they do is sleep. Thought I'd bring them along anyways." Mentally, they winced. They had no idea of what they were saying, and that lie sounded weak even to them.

"Oh, well that's nice of you!" the monster said cheerfully walking next to Chara. The human blinked at them, as the monster kept talking. "So what's your favorite story of Undyne? I mean there's so many and all of them are soooo cool! She is the greatest after all!"

Chara hesitated, not wanting to get caught in the lie of having no clue at all who Undyne was. They shrugged and forced a smirk, they tried to pretend they were simply chatting with Frisk instead of one of the monsters they had slaughtered over and over again so Frisk wouldn't have to.

"I dunno. Like you said there's so many," the words fell easily from Chara's mouth even as their stomach twisted into knots. They couldn't trust anyone. The minute they let their guard down something would happened, it always had and always would.

"True!" the monster said, "My favorite is from before she became Captain of the Guard, but man! She was awesome even back then. Charging up to the king, demanding if he knew what Gaster was doing, and then-! Demanding that we change the way we think about humans! Soooo cool!"

The monster grinned at Chara, a bright innocent expression that remind Chara of Frisk before t- before the experiments worsened. Chara frowned, wondering why their head was starting hurt, and only vaguely listened to the monster chatter on.

"I mean Mom said that we used to try and hunt humans down to break the barrier, but I don't know if I believe her. Pretty much everyone is chill with humans now, except for a small group that still thinks we should take their souls. But Undyne is going to track them down and take them out! Hey! Maybe we can see her do that today!"

The trio stepped into the tunnel that led into Waterfall and Chara realished in the warmth. They glanced around at the walls, wondering what the name for the color was. On their back, Frisk stirred slightly, and Chara set them down, brushing the hair from their face. Frisk opened their eyes, blinking slowly as they nuzzled their cheek into Chara's palm.

"Hey," Chara said, smiling at them softly, "Can you walk?"

Frisk nodded, a small motion, and tried to stand, wobbling on their legs. Chara reached out to steady them, and was surprised as the monster did the same from Frisk's other side.

"Whoa dude," the monster asked worriedly, "Are they supposed to be this warm?"

Chara blinked, roping one of Frisk's arms around their shoulders while the monster did the same with Frisk's other one. Now that it was brought to their attention, and they weren't rushing to escape from anyone, Chara could see how pale Frisk was. Frisk's legs were shaking, and they struggled to breath, sweat dripping down their face.

The monster ducked away, and Chara stumbled at the sudden increase of weight. Frisk was struggling just to stand on their own. Chara felt their own legs shake under the struggle, and they jerked backwards when the monster shoved its face in theirs.

"Dude," the monster said, forehead to forehead with Chara "You're as warm as they are. I think you're sick."

"We're fine," Chara snapped, despite the fact that the longer they stood in the warmer tunnels the hotter they felt as their body temperature rose. The monster stepped back with a frown, and glanced between the two humans.

"You don't look fine," the monster said after a moment, "I- I'm going to get help."

"Wait, no!" Chara's head snapped up as the monster ran off. "Dammit." They shouldered as much of Frisk's weight as they could and took a labored step forward. "Come on Frisk. We need to be gone by the time they come back."

Chara's head felt like it was stuffed full of cotton, and Frisk's eyes were glazed over, but they pressed forward. Chara wasn't sure how far the two of them got before they crashed to the ground, but it was a fair distance. They reached for each other and linked hands, tangling their fingers together.

Frisk squeezed their eyes shut and whimpered, fear etched onto their face. Chara wasn't an expert at reading expressions, but that one had happened enough in the lab that they knew Frisk was hallucinating. They tightened their grip on Frisk's hands, and worried about what their sibling was seeing.

* * *

 _You struggled against the scientists grip as he strapped you to the metal table. The leather cut uncomfortably into your skin, and the more you moved the more it hurt. The scientist ignored you and your resistance, muttering to himself under his breath, something about your movements._

 _Across from you, strapped to their own table, mercifully given back to you in some form, Chara screamed at the skeleton. You weren't sure where the body the ex-ghost was in came from, but you didn't care because Chara was back and you weren't alone in this anymore. A part of you was horrified that you couldn't do anything to block the pain from them anymore, but most of you just clung to the other human throughout the horrors and experiments._

 _Once you were strapped down securely enough, he stepped back to grab his equipment. The large number of restraints were holding your left forearm down, which confused you since normally they were spaced evenly. Chara was in a similar situation, except their whole arm was strapped down._

 _The scientist approached you, scalpel gleaming in his hand, and you tugged harder on the the leather holding you down, feeling sections of your skin break open. Your left arm remained stubbornly still. The blade descended and you winced as it was dragged down your arm lightly, and the across, back up again, and across once more. A rectangle that started to bleed lightly._

 _Horror crawled up your throat because the last time he had done this he had peeled back your skin._

 _Sure enough, he dug his bony finger under the cuts and pulled on the skin. You screamed at the pain as the rectangle tore away from your body inch by inch. You thought that maybe Chara was screaming as well, but your focus had been drawn down to the fire of pain that radiated from your forearm._

 _You were sobbing as the scientist carefully set your strip of skin aside and prodded at the now exposed muscles. Then he grabbed the scalpel again, seemingly oblivious of the red staining his bones. You begged him not to, while Chara screamed at him even louder as he started to saw through your muscles next._

 _You screwed your eyes shut as you felt him tugging, not wanting to watch the muscle be pulled away from the bone. Your stomach was rolling and tears flowed down your face. You didn't want this, you didn't deserve this, this wasn't right. You repeated the mantra in your head over and over again, almost like a comforting lullaby._

 _Then Chara's screams changed from anger to horror._

 _"_ _Stay the hell away from me you freak! Don't you dare!"_

 _You worked up the courage to open your eyes and watched with sick fascination as the scientist cut Chara's arm open as well. Expect there was nothing there. Their arm was just like an inflated balloon made of skin, holding only air between the layers._

 _Chara fell silent in their own horror as they stared at their arm._

 _"_ _It is fascinating," the scientist said to himself, "There sheer number of systems in a human." He glanced at you, and frowned. "Though it seems that I have chosen the wrong ones to start with._

 _He set the strip of muscle next to the strip of skin, and selected a saw that buzzed when he pressed a button on the side of it._

 _"_ _Perhaps I should start there instead. It will be fascinating to study the difference between the bone make up of a skeleton monster and the skeleton of a human," he murmured, as you started to sob again._

 _Then there was pain, and painpainpainpain._

 _You came back to your senses after what felt like forever, breathing hard, and your throat sore from your screaming. Blood dripped from the table you were on, and you hysterically wondered who would clean that up._

 _You turned your head away from your mangled arm, refusing to acknowledge what he had done, to learn how badly he had damaged you this time. There was a crushing silence as the two of you waited for your tormentor to return from whatever he was doing, and your head started to spin from blood loss._

 _"_ _When did he have you Save last?" Chara whispered._

 _"_ _Just before," you replied, and you both fell silent again. You both knew from past experiences that when he did that, it meant that there was a large chance you were going to die because of this and then it would repeat until he figured out how to do whatever he want to accomplish without you dying._

 _The scientist came back, but with a box of. . . something in his arms. He set it down, and paused briefly to heal your arm. You screamed again at the pain of bone, muscle and skin being forcefully regrown, and slumping down as he turned away from you._

 _The scientist reached into the bow and pulled out a bone, one of the ones from the arm that you didn't know the name of._

 _"_ _Replicating the cell make up of Subject F wasn't simple, but I succeeded," the scientist said, placing the bone in Chara's arm as you both watched in horror. It just hovered in the spot it supposed to go as he placed the other bone that went in the forearm next to it. Then he grabbed a needle and thread and started to sew the muscles onto the bone and skin._

 _You turned your head away and tried to ignore Chara's screams._


	5. Chapter 4

A/N- Me: Sorry for the wait guys! Life got hectic!

Muse Kitty: ...

Me: Awww. Kitty, I wasn't ignoring you promise. C'me here girl.

Muse Kitty: Purr

Me: That's right, we've got lotsa chapters done, just need them looked over by the beta

Many thanks to TheFlameRose for betaing!

Disclaimer- I don't own Undertale

* * *

Chapter 4

Chara tried to keep their breathe steady, curling around Frisk as best they could to try and stop the other child from shivering. The fever they both had made the usually warm area feel almost as cold as Snowdin. Chara cursed themself for not recognizing the signs earlier, having headed their panic of being around a skeleton monster, letting it take over their ability to think rationally, and now Frisk would pay the price for it.

They tried to tell themselves that they had done the best they could, but they knew, and felt their heart sink in realization, they should have stayed with the skeleton monsters. They could have played up the weakness until Frisk was better and then made a break for it. Now they were both going to die and end up right back in Gaster's hands.

They could hear the clinking of armor grow closer, and Chara bit down on the inside of their cheeks to keep from making any noise. Maybe if they were really quiet and still, the monster would walk by and Chara could delay the inevitable a little while longer.

"They were over here!" the voice from the monster kid before echoed in Chara's ears, and they fought the urge to groan. Another mistake they could probably blame on their fever, they should have stayed far, far away from any monster despite how nice they seemed at first. Everyone wanted something, and monsters wanted to break the barrier using human souls.

The sound of armor grew closer and Chara tensed, readying themself for whatever they would have to do to protect Frisk. Death was unacceptable, they knew that, but Frisk's death was even more unacceptable.

"There!" the monster kid said, and Chara watched the silver boots move steadily closer, dogged by yellow feet.

They stopped just to the side of Chara, who studied them through half lidded eyes. As the armor-wearing monster crouched down to check the humans out, Chara launched themselves upward with as much strength as they could muster. Their hands landed hard on more metal, and Chara thought they felt a bone snap against it, but they had felt much worse.

The armor bent under the force of the blow, and Chara's desire to hurt the monster wearing it. The monster stumbled back, struggling to keep its feet, and the monster kid watched with wide eyes from the side.

"What-?" a female voice could be heard from underneath the metal helmet, and Chara bared their teeth in a snarl.

"Calm down punk," the monster snarled back, "No one wants to hurt you. We stopped hunting humans years ago."

Chara didn't back down, feeling their body sway as they struggled to stay standing.

"Look," the armored monster said, "Whatever that bastard claiming to be a scientist did was illegal, and I'll see him as dust myself for it. Don't you dare give him another chance to win by dying here and now when you could get help."

Chara stared at them, before letting out a dry chuckle.

"Why would you help me?" Chara protested, "You get nothing from it. Unless you need us healthy to take our souls to break the barrier, in which case you can go screw yourself."

The pain was catching up to Chara, black spots dancing around their vision for the second time in they didn't know how long. They knew they only had moments before the went crashing to the ground and they had to make it count.

Chara took a deep breath, and fell into the stance that Gaster had taught them. From there it was letting muscle memory, and the echos of Frisk's screams guide them forward. If they didn't Fight Frisk would be the one hurt, and that wasn't ok. It would never be ok.

Their feet shot forward first, a scissor kick that Chara didn't even need full vision to aim.

The armored monster surged backwards, eyes widening behind the helmet. Chara kept the attack going, landing on the foot they had kicked with and used that momentum to spin and kick with the other one, ignoring the pain that caused in their injured leg. This one was blocked with a forearm, Chara's shin meeting metal. It buckled under the force and the monster kid made a startled sound.

Still running on instinct, Chara dropped down, and turned to the kid. The easiest target should be taken out first, they could still hear the Doctor's voice, because it could mentally weaken the others as well as lessen the number of people they had to keep track of.

Chara stumbled as they tried to take a step in the kid's direction, vision almost black at this point, but they knew that if they stopped before they passed out then the next battle would be even harder as punishment. Or Frisk would be taken for another round of experimentation instead.

A hand landed on their shoulder, stopping their movements, but keeping them steady.

"What do you think you're doing?" the monster's voice dropped to a deadly octave, and Chara wished they knew how to do that, maybe then everyone would leave the two humans alone.

They opened their mouth to answer, questions that went unanswered were punished, and blacked out.

* * *

Undyne was furious. At herself, at the kids she had just found, but mostly at the Bastard that had started it all.

When she had heard from Sans that there was a couple of human kids running around Snowdin Forest, she almost didn't believe him. It had been years since a human had fallen down into the Underground, and the couple that were still hanging around were adamant that there were legends and later barriers set up to keep people away from the mountain. They shouldn't had to deal with another human, to struggle with keeping the idea of just killing the humans to get out from the kingdom's head.

When Sans told her that they had likely had a run in with Gaster, Undyne may have broken a few things in her anger. The Bastard just couldn't keep his hands away from anything. Even if they hadn't been humans, which Undyne had sworn to protect to make up for the Underground's mistakes; and children, who should never have to go through something like that. Should never have to deal with the nightmares her best friends still had on a regular basis.

The Captain of the Guard had been heading to Gerson to get his thoughts on the Bastard and on the possible paths the humans could take. She would have prefered to talk to one of the humans that were around New Home, but it was too far, and she was running low on time. The guard was taking too long to locate the kids already.

On her way to the old man's shop, a young kid came running up to her shouting about someone needing help, so she hadn't hesitated to follow after them. Her armor slowed her down more than she had liked, but since she didn't know what situation she was going into she was going to keep it on.

Undyne didn't expect to find the humans she had been looking for curled up on the ground. She definitely didn't expect one of the shivering children to launch upward into a near lethal attack, one that probably would have killed her if she hadn't been wearing her armor.

"What-?" she said in surprise, wondering why the human's first reaction was to attack when they obviously didn't have the strength for it. She tried to reassure the kid that everything would be alright, tried to encourage them to keep living so that Gaster wouldn't have an indirect victory in their death, but from the glassy-eyed, distrustful stare, she wasn't going to get anywhere with them.

The response she got sent a brand new shot of anger down her spine. What sort of horrid person teaches, a child no less, that help only comes if someone gets something out of it?!

The kid seemed to zone out as they slipped into a stance that Undyne only vaguely recognized, and shot forward with terrifying speed. The Captain of the Guard found that she could only just keep up with the kid, which was made even worse by the idea that the human seemed out of it and wasn't focusing on the fight in front of them.

Monster Kid startled, and the human turned to them as their attention was drawn. Undyne felt like a bucket of ice had been dumped over her as the human staggered towards Kid with obvious intent to attack them as well.

Undyne reached out to stop, as well as steady the kid, who looked like they were going to keel over at any moment.

"What do you think you're doing?" she warned. She wouldn't hurt the kid, she taken a oath about it, but her duty to the kingdom always came first. Undyne would attack if it came down to it. Which was why it was a relief that the kid collapsed when they did.

She grabbed the kid in one arm, and the other one still on the ground in the other, carrying the two of them easily. Monster Kid was staring at her with a mix of terror, hero worship, and worry.

"What- What's going to happen to them?" the kid whispered, and Undyne admired the fact that they looked ready to leap to the human's defence if they needed to.

"Nothing!" Undyne reassured with one of her sharp-tooth grins. "What happened here wasn't their fault! We can blame it all on the Bast- Gaster," Undyne corrected herself quickly, "So they'll be taken some place they can recover, and then integrated into the kingdom."

Monster Kid bounced up and down on their feet. "So I could visit them later?"

"Sure kid!" Undyne agreed, and watched in amusement as the kid took off, tripped, and got right back up to keep going.

She readjusted her grip on the children, and wondered at how hard it was going to be to keep them safe as they recovered as well as help them learn to trust again. She set off back to her house, making a mental note to call Alphys as soon as she had gotten the humans settled into some makeshift beds. The scientist would want the latest update on the situation, and would be the best bet for helping cure the kids.

After that, Undyne would have to inform the skeleton brothers.

And then Asgore.


	6. Interlude 1

AN- Me: Oh look! A pretty flower!

Muse Kitty: Purr

Disclaimer- I don't own Undertale

Interlude

The screams through the lab that Flowey thought would be never ending had been silent for the past couple of days. The flower that used to be Prince Asriel simply shrugged and turned back to blankly staring at the wall in front of him. It wasn't like it had anything to do with him, and Gaster had long since conducted all of the experiments he could for a soulless being, leaving him here to rot. He had nothing to fear.

The door opened, and Flowey didn't react, his eyes never even blinking.

"Subject A," the detached voice said, and Flowey turned towards him, Non-compliance was punished after all. He resisted the urge to shiver at the look in the doctor's eyes, and he idly wondered how high a level of LOVE the doctor had accumulated after all these years. "You claimed to be Prince Asriel."

He nodded. The doctor hadn't been able to disprove it for all that he didn't believe it, so by the laws of science he had to treat it as true. Flowey knew all about the man's twisted version of science now.

"Then you would be familiar with Subject C's thought process."

Flowly stared at him blankly. He would have to know who Subject C was before he would be able to say anything on that front.

"Subject C," the doctor continued, "Previously identified as Chara Dreemur."

Flowey's eyes widened at the name of his best friend and sibling, feeling something for the first time in a long time. According to the doctor things without souls couldn't feel anything. So either Flowey still had some semblance of a soul or the only feeling he lost was love, because he definitely could feel fear during the experiments, and hatred for the man in front of him.

He looked Gaster in the eye and, for Chara, for his best friend, for his sibling, of the one person he could still cobble together some version of positive emotion, he defied his tormentor for the first time in decades. He said the words that would anger the doctor the most, hopefully keeping him off of Chara's tail for as long as possible while Gaster focused on Flowey.

"You. Can't. Make. Me." he challenged, ignoring the shaking of his body. The doctor's usually detached expression twisted, and Flowey mentally gave a triumphant grin. For Chara, it was all worth it.

The doctor reached out, and Flowey screamed as his world was filled with pain.


End file.
